A proportional solenoid control valve is generally disclosed in U.S. Pat. No. 5,232,196. U.S. Pat. No. 5,232,196 generally discloses an improved arrangement for a proportional solenoid valve for controlling a flow rate with accuracy.
In such proportional solenoid control valve, if magnetic force is weaker, unstable element for controlling is generated such as frictional thread engagement, affection due to inlet pressure and outlet pressure.
In a proportional solenoid valve a displacement is determined based upon power balancing of a attracting magnetic force and a repulsion force, the attracting magnetic force being a force for attracting a magnetic rod and a plunger to one another by a magnetic field generated from a solenoid coil, the repulsion force being due to the displacement of a spring.
When a controlling voltage is changed, an attracting magnetic force is changed, a balancing displacement of a flat spring is changed, so that a flow rate is controlled by a movement of a plunger.
When a magnetic force is made stronger by restoring turbulence in atomic array due to processing surface distortion by employing cylindrical magnetic yoke and magnetic washer by making its size smaller and enlarging magnetic cross sectional area, and when a magnetic flux density is smaller than saturation region by increasing a spring constant of a flat spring for power balancing, hysteresis becomes smaller, affection of a primary side pressure and a secondary side pressure for a flow rate becomes smaller so that stable controlling is realized.